Design of a Dual-Polarized Dual-Band and Wideband Multi-Ring Microstrip Antenna Fed by Two L-Probes with a Cavity Structure for Stable Gain Characteristics

Abstract

This paper presents a dual-polarized dual-band and wideband multi-ring microstrip antenna (MR-MSA) fed by two L-probes with a cavity structure. The proposed antenna consists of two circular ring patches arranged at the top and middle layers of a triple-layered dielectric substrate and two L-probe placed orthogonally in the bottom layer with a large thickness for dual-polarized dual-band and wideband operation. In order to obtain stable gain characteristics against finite sizes of the dielectric substrate and the ground plane, a cavity structure which is composed of a square ring patch on the top layer and several vias connecting to the ground plane is introduced surrounding the radiating patches. The cavity structure is designed in a small size without affecting the dual-band and wideband performance of the MR-MSA by using the numerical simulation with ANSYS HFSS. The design frequencies of the MR-MSA are around 3.5 GHz and 4.75 GHz. The simulated results reveal that dual-band and wideband performance of 26% and 23% fractional bandwidths less than −10 dB reflection is observed. It is also confirmed by the simulation that stable gain characteristics against sizes of the substrate and the ground plane of the designed MR-MSA with the cavity structure are obtained in comparison with the same MR-MSA without the cavity structure.